Resumen en Inglés:

The treatment of Chagas disease (CD) has relied for more than five decades on two drugs, benznidazole (BZ) and nifurtimox (NTX), both with significant limitations and severe adverse effects. Their limited efficacy during the chronic phase underscores the urgent need for new chemotherapeutic strategies. The pursuit of new therapeutic agents for CD is focused on identifying molecular targets essential for Trypanosoma cruzi survival that are either absent or highly divergent in human, thereby enhancing selectivity and minimising off-target toxicity. These targets exploit the parasite's unique biology at multiple levels. Key metabolic vulnerabilities include: ergosterol biosynthesis, a sterol pathway distinct from human cholesterol metabolism; glycosomal metabolism, reflecting parasite´s unique compartmentalisation of glycolysis; and redox homeostasis, which depends on trypanothione rather than glutathione. Additional promising avenues involve the parasite's genetic and epigenetic regulation, mRNA processing and translational control. Furthermore, virulence-associated factors, and specific enzymes such as type I nitroreductase (NTR-1) can be exploited for selective prodrug activation. The complex genomic organisation and pronounced plasticity of T. cruzi complicate the identification of novel therapeutic targets. The abundance of proteins annotated as hypothetical or of unknown function further obscure critical metabolic pathways that could serve as druggable targets. In this context, the discovery of new drugs for CD strategically integrates phenotypic, target-based, and computational approaches, all of which require rigorous validation through preclinical in vitro and in vivo studies. Although modern approaches have yielded several promising lead compounds, successfully controlling CD will also depend on overcoming socioeconomic and access-related barriers to ensure that new therapies reach the populations most affected by this neglected tropical disease.

Resumen en Inglés:

BACKGROUND Chagas disease (CD) is caused by Trypanosoma cruzi. Treatment is based on benznidazole (Bz), although it has significant limitations, such as low efficacy in the chronic phase. Therefore, the search for new therapies with greater selectivity and antiparasitic activity is necessary. In this context, 1,2,4-oxadiazole stands out for its biological properties, including antiparasitic activities. OBJECTIVE To evaluate the in vitro activity of N-cyclohexyl 3-(3-methylphenyl)-1,2,4-oxadiazol-5-amine derivatives against the Y strain of T. cruzi and an in vivo toxicity study. METHODS Cytotoxicity was evaluated in LLC-MK2 cells by the MTT assay, while the antiparasitic effect on the three T. cruzi life forms was determined by counting. Flow cytometry analyses were then conducted to investigate possible death pathway mechanisms and antioxidant and antiacetylcholinesterase activities. Scanning electron microscopy (SEM) was also performed to observe morphological changes caused by the compounds. Finally, in vivo acute toxicity tests were performed on ZebraFish embryos. RESULTS The results presented show distinct cellular toxicity profiles in LLC-MK2 cells, in addition to demonstrating antiparasitic activity at different concentrations. In amastigotes, cytotoxic effects were stimulated. The molecules also induced an increase in reactive oxygen species and membrane damage, in addition to loss of integrity and morphological changes. The antioxidant activity revealed a high capacity for scavenging free radicals, suggesting an alteration of the redox balance of the parasite, in addition to showing inhibition of acetylcholinesterase, an important enzyme present in the formation of parasites, which choline is a constituent. In the ZebraFish model, molecule 2a showed dose-dependent embryonic toxicity, with an LC50 of 14-15 µM. MAIN CONCLUSIONS The calculated conclusions appear to indicate an antiparasitic effect associated with cell death mechanisms. However, further studies are needed to reduce toxicity in the animal model and increase delivery to the site of action.

Resumen en Inglés:

BACKGROUND Benznidazole (BZN) has been used for more than fifty years in the treatment of Chagas disease (CD). It is produced by only three pharmaceutical companies worldwide: Lafepe (Brazil); Elea (Argentina) and Liconsa (Spain). The therapeutic interchangeability among these products has never been evaluated. OBJECTIVES To assess bioequivalence between three 100 mg BZN formulations. METHODS Pharmaceutical equivalence, with dissolution testing, was assessed prior to the bioequivalence study. For bioequivalence, healthy adult participants received 100 mg of BZN formulations after meal, in a randomised clinical trial. Blood BZN concentrations were measured. Pharmacokinetic parameters were determined by non-compartmental analysis. FINDINGS The BZN Liconsa demonstrated faster in vitro dissolution. However, bioavailability was not different between formulations. The mean area under the curve (AUC)84h values were 49431.22 h*ng/mL (SD = 9938.53) to Lafepe, 48974.38 h*ng/mL (SD = 10304.67) to Elea and 48204.17 h*ng/mL (SD = 9342.18) to Liconsa. The mean Cmax values were 2339.23 ng/mL (SD = 445.53) for Lafepe, 2209.04 ng/mL (SD = 448.02) for Elea and 2303.90 ng/mL (SD = 431.41) for Liconsa. The mean tmax was not different between formulations. AUC were higher in women for Elea (20%) and Lafepe (27%). The adverse events did not differ between sexes. MAIN CONCLUSIONS The 100 mg BZN formulations demonstrated bioequivalence.